UHPC Innovations for Durability and Resiliency

Transcription

1 UHPC Innovations for Durability and Resiliency Ben Graybeal leads the Structural Concrete Research Program for the Federal Highway Administration at the Turner- Fairbank Highway Research Center in McLean, Virginia. He received his B.S. and M.S. degrees from Lehigh University and his Ph.D. from the University of Maryland. His research interests include structural application of advanced cementitious materials, concrete material characterization, experimental evaluation of highway bridge structures, and non-destructive evaluation techniques. ACI Fall 2013 Convention October 20-24, Phoenix, AZ WEB SESSIONS WEB SESSIONS Ben Graybeal, Ph.D., P.E. Structural Concrete Research Program Mgr. Federal Highway Administration AFGC UHPC Recommendations: Chapter 3 Durability: Conclusion The values obtained for UHPFRC in general show a very marked improvement in durability compared with ordinary cementitious materials and corroborate the viability of long project life cycles with reduced concrete cover. This can be explained by their particular porous structure characterized by an absence of capillary porosity and non-interconnected porosity on a very small scale. Association Française de Génie Civil Bétons Fibres Á Ultra-Hautes Performances: Recommandations Revised Edition, June 2013 Section FHWA HRT Published in June references 600+ item bibliography FHWA HRT Published in August 2006 Extensive testing of a UHPC Includes durability testing Mix Designs, Material Properties, Design Guidelines, Deployment, etc

2 ASCE Journal of Materials in CE Published in October 2007 Graybeal and Tanesi V. 19, No. 10, p NTIS PB Published in January 2013 Extensive testing of a grouts for PBES Includes durability testing Rapid Chloride Penetration (ASTM C1202) Total Charge Passed * Steam Treated (2006) 18 Coulombs Ambient Cure (2006) 360 Coulombs Ambient Cure (2012) 400 Coulombs * Charge Passed Rating < 100 Negligible 100 to 1000 Very Low 1000 to 2000 Low 2000 to 4000 Moderate > 4000 High Relative Dynamic Modulus* Steam Treated (2006, unsaturated) 97% Ambient Cure (2006, unsaturated) 112% Ambient Cure (2012, saturated) 99% * C666 Procedure A for 600 cycles 2

3 Scaling Resistance (ASTM C672) Abrasion Resistance (ASTM C944) Weight Loss per Abrading * Steam Treatment 0.18 grams Ambient Cure 1.18 grams Initial Condition After 50 Cycles Surface Condition Rating: 0 (no scaling) * ASTM C944 with Ground Surface Alkali-Silica Reaction (ASTM C1260) 14-day Expansion* Steam Treated (2006) 0.01% 1-day Ambient Cure (2006) 0.00% 28-day Ambient Cure (2006) 0.01% UHPC Durability: Very Good * Expansion < 0.10% considered innocuous UHPC Durability: Very Good NTIS PB Published in January 2010 Performance of Cracked UHPC But what if it cracks 3

4 Load Salt Water 6 months continuous: Cyclic Flexural Loading Salt Solution Exposure No degradation in flexural response No indication of steel fiber reinforcement failure across cracks Prism extracted from flexural tensile face. Loaded in direct tension. Tensile failures at newly generated cracks. Tensile failures at 1.9, 2.3, and 2.6 ksi. Old cracks intersected, but generally not followed. Salt residue visible near salted face. No indication of steel fiber deterioration. Proceedings of fib 2010 Meade and Graybeal Flexural Response of Lightly Reinforced UHPC Beams 4

5 2 vol. % SF Mean Crack Width = mm 1 vol. % SF Mean Crack Width = mm 200X 800X mm 0.1 mm Ben Graybeal, Ph.D., P.E. Structural Concrete Research Program Mgr. Federal Highway Administration benjamin.graybeal@dot.gov 5